The LED has gained wide use in illumination technologies with a wide variety of applications, such as watches, calculators, remote controls, indicator lights, and backlights for many common devices and household devices. The technology is advancing at a rapid pace and new applications continue to emerge as the brightness and efficiency of LEDs increase.
LEDs typically include a PN junction diode semiconductor that emits photons when voltage is applied. This process of photon emission is called injection electroluminescence and occurs when electrons move from the N-type material to fill the lower energy holes that exist in the P-type material. When the high energy electrons fall into these holes, they lose some of their energy which results in the generation of photons. The materials used for the p-type and n-type layers along with the size of the gap between them determine the wavelength and overall energy level of the light that is produced.
Recent innovations in the manufacturing of the die material and packaging have resulted in ultra high brightness capabilities. The use of new materials for the substrate has allowed for improved thermal conductivity that allows for higher power consumption and net light output. This increase in light output has enabled new application for LEDs, such as automotive lighting, traffic signals, and more recently television displays.
Improvements in the types of material used to construct the LED have allowed for improved brightness. These improvements enable system designs that can produce better color fidelity at near equivalent brightness to common lamp-based technologies with longer lifetimes, which makes their application well suited to applications using a digital micromirror device (DMD).
As LED technology developments continue to improve brightness and reliability, LED illumination may become more of a mainstream light source for many future applications. Future developments will be able to take further advantage of the fast LED switching time to improve video performance, enhance contrast without opto-mechanical components, and create adjustable color gamuts that far exceed the possibilities of traditional illumination sources.